羟基聚丁二烯羟值测定新方法

本文建立了两个相关的∑Aa_i-B_2型凝胶化反应方程,含试样官能团数和重均官能度两个未知数.解联立方程,得到一元二次方程.通过测定该方程的系数,间接测得试样官能团数和重均官能度.该方法用于H_2O_2引发的羟基聚丁二烯羟值测定。其结果比目前国内外通用的经典酰化法高一倍以上.证明新的羟值数据是正确的.     

薄层色谱法测定溴端基聚丁二烯官能度分布

遥爪型预聚物端基聚丁二烯广用于液体橡胶、粘合剂、固体燃料和加成衍生物制品,其宫能度分布对化学物理性能有重大影响。1971年Ronald利用LC和GPC测定羟基和羧基聚丁二烯的官能度和分子量分布,其法较繁。1975年Anderson等用显色团取代羟基以增加对紫外光波的检测灵敏度从而改进了前法,1977年日本东京大学T.i.Min等用TLC成功地测定了阴离子聚合制得的羟端基聚丁二烯的官能度分布。此法简洁快捷。来自阴离子聚合的样品,其分子量分布很窄;d≈1,1.2-结构达85～95％,产品纯净易于层析,与此不同,由乳液聚合的溴     

红外光谱法测定端羟基聚丁二烯(HTPB)胶粘体系的固化度

介绍用红外光谱法测定端羟基聚丁二烯（HTPB）胶粘体系固化度的原理及方法，并对端羟基聚丁二烯胶粘体系固化过程进行监控，分析了一定温度下胶粘体系的固化度与固化时间，以及相同固化时间内胶粘体系的固化度与固化温度之间的数学关系。     

端羟基液体聚丁二烯微观结构的13C-NMR研究

本文研究了在乙醇溶剂中用过氧化氢引发聚合的端羟基液体聚丁二烯(简称丁羟)的¹³C-NMR谱,发现了RCH=CHCH₂OH(反式)和RR′C=CHCH₂OH共振峰,肯定了这两种端基结构。确定了在聚合过程中乙醇转移到分子链端的主要结构是RCH=CHCH₂CH(OH)CH₃(顺式和反式),它占羟基总量8%左右。工作还确认,在丁羟中尚存在少量的长支化结构以及醇、醛端基结构。     

胶液法制备高顺式端羟基聚丁二烯液体橡胶

以工业顺丁胶原液为起始原料,先经氧化裂解反应制得醛基封端的聚丁二烯液体橡胶,再经还原反应制得了端羟基聚丁二烯液体橡胶.结果表明,反应过程中顺丁胶的微观结构未发生异构化,所得的端羟基聚丁二烯液体橡胶的顺式含量高(cis-1,495%);分子量通过控制氧化裂解反应物与丁二烯结构单元的化学计量比,在2200~7000间可调(~1H-NMR法);分子量分布指数维持在1.5~2.1范围;官能度(fn)在2.0左右.与阴离子聚合型丁羟胶和自由基聚合型丁羟胶相比,氧化裂解法制备的丁羟胶微观结构更规整,顺式含量更高,能够保持极低的玻璃化转变温度.此外,以工业顺丁胶原液为原料,既省去了顺丁块胶生产的水析凝聚、干燥压块等过程,又免去了胶块剪切破碎、溶胀溶解等过程,大幅度减少了能量消耗,且反应条件温和、可控、高效、经济,具有良好的工业化前景.     

红外吸收法测定钢中碳量的测量不确定度评定

对高频炉燃烧.红外吸收法测定钢中碳含量的测量不确定度来源进行了详细的分析,建立了合理的数学模型,概述了物质称量、标准物质认定值、测量的重复性等等各主要的不确定度分量的评定方法,对高频炉燃烧.红外吸收法测定钢中碳含量的测量不确定度进行了仔细的评定,给出了扩展不确定度,并就其对钢中碳含量测量结果的影响进行了深入的探讨.     

线性/三臂星型端羟基聚丁二烯的活性负离子聚合及其表征

在环己烷溶剂中,以自制的叔丁基二甲基硅氧基丙基锂为引发剂,丁二烯为单体,四氢呋喃为结构调节剂,采用活性负离子聚合法合成了线形端羟基聚丁二烯(L-HTPB).在此基础上,以甲基三氯硅烷为偶联剂合成了星形端羟基聚丁二烯(S-HTPB).采用GPC和1H-NMR对L-HTPB和S-HTPB结构进行了表征,结果表明,采用负离子聚合法合成的2种聚合物具有相同的微观结构,且线形端羟基聚丁二烯的平均官能度大于1.9,星形端羟基聚丁二烯的平均支化度和平均官能度大于2.8,与理论设计值基本相符.另外,实验中通过调节溶剂中环己烷和四氢呋喃的比例来控制聚合物主链的微观结构.实验结果证实,随复配溶剂中环己烷用量的增加,聚合物1,4-结构相对含量逐渐增大,特别是顺式1,4-结构相对含量增大的趋势比较明显;当聚合溶剂采用单一的环己烷时,聚合物主链1,4-结构相对含量大于90%,顺式1,4-结构相对含量高达70%以上,聚合物主链中1,2-结构相对含量约为5.70%;相反,当聚合溶剂采用单一的四氢呋喃时,聚合物主链1,2-结构相对含量大于90%,而顺式1,4-结构相对含量趋于0,样品的外观表现为塑料.     

核磁共振内标法测定聚酯羟值

合成了14种不同组成的聚酯样品以考察聚酯端羟基α-H的1H谱谱峰特点。利用聚酯端羟基α-H的1H谱谱峰与聚酯其它峰互不干扰的特点,采用优化的1H谱脉冲序列和检测参数,以苯乙烯为内标,建立了一种用核磁共振1H谱检测聚酯端羟基α-H在聚酯中的含量,再根据端羟基α-H与羟基的比例关系求聚酯羟值的方法。结果显示,其测量的相对偏差小于1%,测量精密度为±0.2。本方法简单、快速、准确度高。     

氯化端羟基液体聚丁二烯的合成和固化

Ⅰ.端羟基液体聚丁二烯的氯化 合成了一系列氯含量不同(5%～68%)的氯化丁羟。利用红外光谱、核磁共振观察了它们的双键变化。上述结果及氯含量与反应时间的关系表明:丁羟在四氯化碳中氯化时,首先进行加成反应,待双键饱和后,进行取代反应。     

环氧丁羟型聚氨酯弹性体的制备与性能

以间氯过氧苯甲酸(mCPBA)为氧化剂对降解法制备的端羟基聚丁二烯(DHTPB)中的部分双键进行环氧化改性,通过控制mCPBA和双键的比例制得具有不同环氧率的环氧化端羟基聚丁二烯(EHTPB),经1H-NMR分析测试表明EHTPB的环氧率分别为5%、10%和15%,与设计值基本一致.进一步以EHTPB为多元醇、4,4'-二苯基甲烷二异氰酸酯(MDI)为异氰酸酯、1,4-丁二醇为扩链剂制备了环氧丁羟型聚氨酯弹性体(EPU),并对其性能进行了测试,研究结果表明:丁羟胶的环氧化改性对聚氨酯弹性体的力学性有着一定的提升作用,其杨氏模量和拉伸强度随环氧率的上升而提高,而断裂伸长率则随环氧率的上升有所下降;环氧丁羟型聚氨酯弹性具有优异的弹性恢复能力;环氧化改性后,聚氨酯弹性体的热稳定性有一定程度的提高;聚氨酯弹性体的玻璃化转变温度随环氧率的上升而升高.     

Butacene合成方法的改进及性能研究

与以二茂铁,4-氯丁酰氯为原料的传统合成方法不同,直接以γ-二茂铁丁酸为原料,采用NaBH4-I2-THF体系代替有毒的锌汞齐作为还原剂,以SOCl2为氯代试剂,制备了4-氯丁基二茂铁,将其与镁粉反应制得格式试剂,再与二甲基氯硅烷反应合成4-二茂铁丁基二甲基硅烷,在高效可重复使用铂催化剂(二氧化硅负载壳聚糖络合氯铂酸SiO2-CS-Pt)催化下与端羟基聚丁二烯(HTPB)硅氢加成得到高收率的巴特辛(Butacene).采用1H-NMR和FTIR对其化学结构进行了表征,采用TGA分析了产物的热性能,并测定了接枝率和羟值.研究结果表明,所得产物与目标产物相符,初始热分解温度提前,热敏感度增加,热稳定性增加,具有良好的催化性能.     

Facile Synthesis of Polyhydroxylated Polybutadiene Derived from Hydroxyl-Terminated Polybutadiene via Thiol-Ene Click Reaction

Polyhydroxylated polybutadiene (PHPB) was synthesized via a thiol-ene click reaction between hydroxyl-terminated polybutadiene (HTPB) and 2-mercaptoethanol (ME) with 2,2’-azoisobutyronitrile (AIBN) as initiator. Effects of AIBN content, reaction time and temperature on the click reaction were investigated by determining hydroxyl value of the PHPB. The PHPB was characterized by FT-IR, ¹H-NMR, ¹³C-NMR and GPC. Relative reactivity of three types of C?C double bonds (1,2-vinyl, 1,4-cis and 1,4-trans units) in the HTPB reacting with the ME was discussed. The results showed that the optimal reaction conditions were that the AIBN content, reaction time and temperature were 2.0 wt%, 180 min and 70°C, respectively. Under these conditions, the hydroxyl value of the PHPB was 3.12 mmol·g^?1 when the HTPB/ME mass ratio was 10:2. All three types of C?C double bonds in the HTPB could react with the ME and the reactivity order was: 1,2-vinyl unit > 1,4-cis unit > 1,4-trans unit.     

Synthesis of hydroxyl-terminated polybutadiene possessing high content of 1,4-units via anionic polymerization

<正>The hydroxyl-terminated polybutadiene(HTPB) possessing high content of 1,4-units was synthesized by anionic polymerization of butadiene,using alkyllithium containing silicon-protected hydroxyl group as initiator and cyclohexane as solvent.The polymers were characterized by GPC,IR and ~1H-NMR.The mechanical properties of cured films were also evaluated.The results show that the content of 1,4-units for HTPBs made by anionic polymerization reaches up to 90%.The molecular weight distribution is very narrow(≤1.05).The functionality of hydroxyl groups approaches 2.Compared with free radical HTPB,the elongation at break of anionic HTPB films increased by 70%,while the tensile strength remained nearly unchanged.This new HTPB can be very useful in solid propellant.     

丁苯、丁腈基聚氨酯的形态与性能

用示差扫描量热法 (DSC)、红外分光光度计 (FTIR)和原子力显微镜 (AFM)研究了端羟基聚丁二烯 苯乙烯共聚物 (HTBS)、端羟基聚丁二烯 丙烯腈共聚物 (HTBN)和端羟基聚丁二烯 (HTPB)与甲苯二异氰酸酯、1 ,4 丁二醇构成的溶液法聚二烯烃基聚氨酯 (PU)的形态结构 .结果表明HTPB和HTBS基PU的相分离程度很大 ,而HTBN基PU的相分离程度小 .这可能归因于HTBS软段的极性低 ,不能与硬段形成氢键 ,而HTBN软段中的腈基具有很强的极性 ,且可以与硬段形成氢键作用 ,增加了软硬段间的相容性 ,相分离程度明显降低 .AFM表明HTBN PU随着硬段含量提高 ,表面粗糙度增大 ,由软段为连续相逐渐过渡到双连续结构 .在硬段含量 6 3%时 ,HTBN和HTPB基PU均呈双连续结构 ,而HTBS PU中硬段为连续相 .HTBN PU软段的相区尺寸在1 2nm左右 ,表面粗糙度较大 ,HPBS PU软段的相区尺寸在 1 1nm左右 ,表面粗糙度最小 ,HTPB PU存在 1 4nm和 5 0nm大小不等的软段相区尺寸 .力学性能表明 ,在软段中引入苯乙烯和丙烯腈结构 ,可使聚氨酯抗张强度分别提高 1 5和 2倍 ,模量和断裂伸长率也明显提高     

Sorption and diffusion of ethanol vapor in polybutadiene/acrylonitrile, polybutadiene/styrene and polybutadiene based polyurethanes

The sorption and diffusion behavior of ethanol vapor in series of polyolefine based polyurethanes (PU) made from hydroxyl-terminated polybutadiene/acrylonitrile (HTBN), hydroxyl-terminated polybutadiene/styrene (HTBS) and hydroxyl-terminated polybutadiene (HTPB) were investigated by using the quartz-spring, DSC, FTIR and AFM. The equilibrium absorption reduced with increasing content of hard segments for all the three types of PUs. The values of the maximum absorption were in the order of HTBN > HTBS > HTPB based PU and related to their composition. The non-Fickian diffusion was confirmed and the sorption was discovered mainly in the hard segments. The HTBN based PU revealed different sorption and diffusion behavior from the other two, which was resulted from its hydrogen bonding not only between ethanol and hard segments but also soft segments. The morphologies of PUs before and after ethanol absorption were also compared. The HTBN based PU showed the most evident phase re-congregation after ethanol absorption.     

Thermal oxidation of polybutadiene. Part 1: Effect of temperature, oxygen pressure and sample thickness on the thermal oxidation of hydroxyl-terminated polybutadiene

An additive-free, uncrosslinked, hydroxyl-terminated polybutadiene of predominant trans 1-4 structure was thermally oxidized at temperatures ranging from 60 to 120 °C, under various oxygen pressures (between 0.01 and 3.1 MPa). Samples of thickness ranging from 5 to 1000 μm were studied by gravimetry (mass changes due to oxygen absorption) and infrared spectrophotometry (hydroxyl and carbonyl build-up, double bond consumption). The effects of film thickness, oxygen pressure and temperature on oxidation kinetics are discussed in terms of branched radical chain mechanisms.     

环氧丙烷-四氢呋喃共聚醚醇的官能度分布

应用液-固硅胶柱层析法,以石油醚-乙酸乙酯-异丙醇不同配比为逐段梯度淋洗剂,将环氧丙烷-四氢呋喃共聚醚醇按官能度进行分离。各级份的数均分子量(M_n)和羟基当量(M_E)分别用气相渗透压法(VPO)和红外光谱法测定。根据各级份的官能度(f_n=M_n/M_E),通过计算可得到共聚醚醇的官能度分布,即零、一、二和三官能度组份的相对含量。计算的各种平均官能度与其它方法的测定值相接近。评价了柱层析法的测定准确性和重复性,证明本文提出的方法对测定共聚醚醇官能度分布是有效、可靠的。     

蒸馏法测定化肥中氮含量的测量不确定度评定

对蒸馏法测定化肥中氮含量的测量不确定度进行了评定。分析了蒸馏法测定化肥中氮含量的不确定度的主要来源,通过数学模型对各不确定度分量进行了评定,采用蒸馏法测定化肥中氮含量的扩展不确定度为0．07％。     

二级标准粘度液定值的不确定度评定

简述了测量运动粘度的基本原理,根据运动粘度的计算公式,将二级标准粘度液定值的不确定度分解成测量方法引入的不确定度、标准粘度计常数引入的不确定度、流动时间引入的不确定度和标准粘度液的不稳定性引入的不确定度。通过调整、忽略、修正或评定对不确定度分量进行处理。     

The effects of polydispersity,entanglements, and crosslinks on pulsed-gradient NMR diffusion experiments in polymer melts

We have used the pulsed-gradient spin-echo NMR method to measure diffusion in a highly polydisperse polymer, a hydroxyl-terminated polybutadiene. We have modelled the expected spin-echo attenuation assuming that the low-molecular-weight fractions are unentangled and constitute a Rouse-like diluent to the entangled larger molecules. Fitting this simulation to our data is consistent with the model and permits the extraction of the range of diffusivities and a semiquantitative value for the molecular weight above which entanglements inhibit diffusion. The model is extended to include a monodisperse diluent present additionally, e.g., a curing agent. This extension is tentatively applied to polybutadiene resins undergoing curing and shows that the diffusivity of the remaining unreacted curing agent is little affected by network formation, whereas the retardation of the unreacted polymer molecules is clearly evident.